Fuel injection pump



Jan. 2v2, 1.946. y G. P. LUM

FUEL INJECTION PUMP Filed Aug. 5, 1943 IlIlllIlll/l 659,765 Ua/V BYATTMA/EY IN VENT 0R Patented Jnn. 2,/1946v Bendix Aviation Corporation,

South Bend,

Ind., a corporation of Delaware Anpunnunn August 5, 1943, senni No.491,529

11 Claims.

This invention relates -in `its broader aspect to means for eecting neadjustments in mechanical devices, and is particularly shown anddescribed herein, by way of example, as appliedto mechanisms foradjusting the effective pumping strokeof plungers `or pistons of rfuelinjection pumps. I I

As is well known in therart, it is highly desirable `to have extremeaccuracy in the metering of the fuel delivered by fuel injection pumpsto the end that the quantities of fuel delivered by the individualplungers of the pump should be as nearly equal as possible. It is alsoimportant in pumps ofthis character t'o time the delivery of Y the fuelwith extreme accuracy, both as to the commencement of the deliverystroke and as to the ending thereof, but even'with careful precisionmanufacturing methods it has been found in practice that there areunavoidable variations in the diameters of the variousl plungers orpistons, the spacing of the cut-od annali and fuel ports, et cetera.lhese variations result in a de'- livery of unequal quantities of fuelfrom the individual pump plungers which causes uneven operation of theengine, a, loss in maximum available power, and a decrease in engineperformauceand' economy. Various means. have been proposed heretofore toadjust the edective fuel delivery stroke of the various plungers of fuelinjection pumps to' compensate for the-aforo? have not proven entirelyksatisiactory for various reasons. f

llt is therefore an important object of the present invention to providemeans for adjusting vthe edective stroke of the plungers of fuelinjection pumps with extreme accuracy to compencate for variousinaccuracies inthe manufacture of the pump', plungers and operativelyassociated parts which adversely .affect the uniformity inthe fueldelivery from the individual plungers oi' the pump.

Another object of the invention is tov provide means for effecting afine longitudinal adjustment which may be particularly useful inconnection with sleeve assemblies for fuel pumps of the above type butwhich is capable of general application in arrangements wherein a unelongitudinal adjustment is requiresl between ndjacent or cooperatingparts.

It is another object of the invention to'prosimple and effective lockingmeans for retaining'the assembly in adjusted positions, said lockingmeans being readily releasable for making adjustments.

Still another object of the invention is to providenovel means formaking various extremely accurate adjustments between parts of amechanism.

The characteristics and advantages of the invention are furthersuiiiciently referred to in connection with the following detailed'description of the accompanying drawing, which represents a preferredembodiment of said invention. After considering this example, skilledpersons will understand thatfthe adjustable mechanism, here disclosed issuitable'to many uses, and that many variations may be made withoutdeparting from the principles disclosed; and I contemplate theemployment of any structures,

arrangements, or modes of operation, that are properly within the scopeof the appended claims.

in the drawing: y Figure l is a sectional view of a fuel injection pumpembodying the present invention;-

iiligure 2 is a longitudinal section of the adinstable by-pass sleeveassembly: @11d Figure 3 is an isometric exploded view of the parts oftheby-pass sleeve assembly.

Referringmore particularly to the fuel injection pump shown in Figure 1,said pump includes va main drive shaft it which drives a member l2 'imthrough an Oldham type universal coupling of mentioned manufacturingvariations, but these known construction, indicated at llt. A locatingpin lo `is provided to prevent incorrect assembly of the coupling whichwould change the ially arranged relative to the tappets to and areslidably received in bushings 26 which form the individual pumpcylinders. In view of the fact that each ofthe tappet and plungerassemblies and the control mechanism therefor are all alike, thefollowing detailed description will be directed to the upper plunger andtappet. A spring 28 cooperates with a washer' supported on a horseshoeor split retainer 29 received in"a groove in the plunger 24 and urgesthe plungerto the left,

maintaining the plunger and tappet in con-l stant contact with eachother and maintaining vide an arrangement of this character having toYthetappet against the wobble plate I8. yThe plungerand tappet arepreferably made as separate abutting pieces rather than as one piece, sothat minor variations in alignment of the bushings .22 and 28 may beaccommodated without tending to bind the assembly. A spring 30 isprovided to move the tappet out of engagement with the wobbleplate inthe event the plunger 24 becomes stuck. 'I'he pumping plunger 24 isprovided with a central bore 32 in communication with a pair. of spacedannuli 34 and 36. An externally threaded by-pass sleeve or member 38,best shown in Figures 2 and 3, is slidably mounted on the plunger 24'and includes an 'outwardly extending ilange 48 having a plurality ofnotches 42 equally spaced about the periphery thereof. Threadablyreceived on the sleeve is a member 44 which is carried by a plate 46thelatter being provided circumferentially with' spaced apart notchesadapted to be snugly received in a grooved portion 48 of the member 44.The plunger 24 prevents the assembled sleeve 38 and member 44 fromsliding out of the cooperating notch and the sides of the groove 48prevent longitudinal movement of the member 44 relative to the plate 46.Although the width of the groove 48 is such that there is nolongitudinal movement of the member 44 relative to the plate said memberis. free to rotate within the notch of the plate, it being considereddesirable to allow such rotation. The end of the member 44 adjacent theange 40 of sleeve 38 is provided with an annular coaxial recess 58 andan annular flange-like wall 5| projecting toward the ilange 48, the wall8l being provided with a plurality of notches 52 equally spacedcircumferentially of said flange. In the form illustrated the ilange 48is' provided with one more notches than is the wall however the numberof notches on the Wall and ange may be 8 varied to obtain any desirediineness of adjustment. Means for locking the sleeve in adjustedpositions comprises a spring 64 carried by and disposed about the sleeve38 and the adjacent end portion 58 of the grooved member 44. This springis provided with a bent end section 88 the free end of which is adaptedto be selectively received in notches 42 of the flange 48 and a curvedportion 68 at the other end-of said section 88 is arranged toselectively engage notches 82 of the member 44, it being understood thatwith the parts in 'assembled relation the spring expands and one endthereof fits within thel recess 58, see Figure 2. If desired the pumpmay be provided with removable plugs 6| positioned adjacent the'respective sleeve assemblies to permit adjustments `of said sleeves, ina manner to be hereinafter described, without disassemblingthe pump.

'I'.he plate 4 8 is secured to a slidably mounted piston 62 which isurged to the right by a spring 64 and is moved to the left against thespring by a rod 88 pivotally connected to one end of a lever 68 havingits other end pivotally connected to a link 'III secured to a diaphragmI2 which forms a movable wall between the interior of the pump and achamber I4 which may be connected to a venturi in the induction passageof a charge forming device, not shown, by means of a passage I6. Theeffective fuel delivery of the pump is varied by variations in pressureon diaphragm 12' as fully explained in the copending Evans applicationfor a Charge forming device, Serial No. 475,783, filed February 13,1943. The left end oi.' rod 88 is of a rounded conical shape and isabuttingly received in a rounded conical ldepression in a member 18secured to the piston 82. This construction facilitates assembly andpermitsthe necessary slight rocking .movement of rod 88 upon movement oflever 88. The interior of the housing' of the vpump forms a fuelreservoir 88 which 7 receives fuel from a suitable source through aconduit 82. l

The operation of the pump shown in Figure 1 is as follows, starting withthe upper plunger in its extreme right-hand position corresponding tothe end of the stroke: Upon rotation of the wobble plate I8, the plunger24 will move to the left until the annulus 34 passes to the left. of theby-pass sleeve 38. At this time, fuel enters through the annulus 34 andbore 32 to illl the pumping space to the right of the end of plunger 24.Upon movement of the plunger to the right, fuel will be pumped back outof the annulus 34 until it passes into lapped relation with by-passsleeve 38 which determines the beginning of injection. Further movementof the plunger forces the trapped fuel past a spring loaded check valve84 into a passage 88, thence to a nozzle supply pipe and nozzle, notshown, which discharges the fuel under high pressure into the enginecylinder. Fuel is discharged from the nozzle until the annulus 36 passesinto registry with an annulus 88 vented to the reservoir 88, whereuponthe remaining fuel in the cylinder of plunger 24 is pumped into thereservoir 88. This arrangement suddenly relieves the pressure of thefuel being pumped and quickly cuts oir injection, thereby eliminatingdripping at the nozzle. Preferably the annulus 38 and the annulus 88 arebrought into registry shortly before the end of the stroke of plunger24v so that the latter portion of the stroke,

which is at a rapidly decreasing plunger velocity o which would producea decreasing fuel injection pressure, will not be utilized for injectingfuel into the engine. This confines the injection period to therelatively high velocity period of the plunger and the resulting highinjection pressure period, whereby better atomization at the nozzle isobtained.

Movement of the by-pass sleeve 38 to the right increases the portion ofthe stroke during rwhich the annulus 34 is open to the reservoir, or in'other words delays the beginningof injection, and consequently reducesthe effective stroke of the plunger. If the by-pass sleeve 38 is movedto its lextreme right-hand position, the annulus 34 does not lap thesleeve 38 at all, or at least not until the annulus 36 isin registrywith the annulus 88, and as a consequence no fuel would be injected intothe engine; however, if desired a stop may be provided to limit movementof plate 46 and sleeve 38 to the right to thereby determine the minimumeffective stroke of the plungers 24. Thus by varying the position ofsleeve 38 the eifective pumping capacity of the pump may be varied fromzero or any desired minimum value to the maximum capacity of the Dump.

In order to eliminate variations in the quantity of fuel pumped by theindividual plungers resulting from variations inthe relative locationsof the annuli 34. 38 and l88, and variations in the diameters of theplungers which may occur during manufacturing of same, each of thebypass sleeves 38 is adjustable relative to the plate -48. Theadjustment of the sleeves in accordance with the present invention isextremely accurate, and minuteadjustments may be effected.

Bearing in mind that, one of the members 38, 44 has one more notch thanthe other, as illustrated, it is possible to adjust each of the sleeves38 laterally relative to the plate 48 in increments equal to the pitchof the thread onl member 38 divided by the product of the number ofnotches .on said members 38 and 44. Thus, for example,

acess if there are six notches on one member and seven on the other andthe pitch of the thread is one thirty-second of an inch, the available'increment of adjustment'is the product of one thirty-#second times oneforty-second, or approximately seven ten-thousandths of aninch. Toeffect the smallest increment oi' adjustment available one portion ofthe bent end section 58 Vof spring Il, as for example, the curvedportion 6l. ismoved out of the respective notch 52 in which it may bepositioned by compressing spring fand the sleeve 44 rotated relative tothe member l0 and the spring-until said portion 60 of the spring engagesthe next adjacent notch 52. This effects an adjustment of one seventh ofa revolu l tion. Then the other or free end portion "of the section 58of the spring is lifted up and so moved out of engagement'withthe notchVI2 in which it is receivedvand thedsleeve Il and spring rotatedtogether in the reverse direction until said free end engages the nextadjacent notch 42 of member 40. d This effects an adjustment in theopposite direction of one-sixth of Aa revolution and as a consequencethe net adjustment is equivalent to the difference between one-sixth andone-seventh, or one forty-second of a revoluas the i'lange on the part;a plurality o'f notches in the ilangeoi the member equally spaced aboutthe periphery thereof; and spring latching means having a portionmovable longitudinally relative to the 'device and slidablyengageablewwith the notches of said part and said member.

3. The'invention dened bylclaim v2 wherein the spring is coiled aboutthe part between its Iilange and the member and said spring portionincludes a curved section; the free end of the end portion being adaptedto engage the notches of one ange and the curved section being 'adaptedto engage the notches of the other ilange. 4

4. In an adjusting device: an externally threaded sleeve part; anannular flange adjacent one end of the sleeve; a plurality of notchesequally d spaced about the periphery of the ilange; an antion. Thus itwill be apparent that extremely ilne adjustmentsl may be made with thepresent invention. However, while the number of,

notches in the respective parts of a sleeve assembly havebeen given assix and seven itis to be understood that any other suitable number ofnotches may be used in the respective parts,

nular groove in the inner face of the ilange; an annular-ly grooved partthreadably received on the sleeve; a reduced end portion of the secondmentioned part extending toward the ilange on the sleeve; a plurality ofnotches4 in the second mentioned part adjacent the reduced end porltion, said notches being equally spaced aboutthe periphery thereof,there being a different number of notches in said second mentioned partthan in the flange of the sleeve part; a spring coiled about the sleeveand reduced end portion and having the coiled ends received in thegrooves in the ange and adjacent end of the Esecond mentioned partv andhaving a bent end section extending longitudinally relative to the axisof the parts, there being an outwardly curved portion as heretofore setforth, it being-understood that the notches of Yeach member, if greaterthan one, are equally spaced relativeto their `respective members. It isto be further unf erstood that while in the present example one parthasonemore notch than the other said part may have two or three morenotches than said other or anyother number that may be 'desired inconnection 'with any particular installation. Obviously, the thread maybe of any desired pitch.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and though saidinventtion has been illustrated in connection with but one modificationthereof it will be apparent that justable relative to each other;locking .means comprising a coiled spring carried on at least one ofsaid members and having a longitudinally extending end portion; aplurality or circumferentially equally Vspaced recesses on one memberengageable with the end'portio'n:` and a plurality of circumferentiallyequally spaced recesses on the other member also engageable with the endportion, .there being a different number of said equally spaced means onone member than on the other member, said longitudinal portion of insaid longitudinally extending'end section of the spring, a portion ofthe free end oi said longitudinally extending end section being'adaptedto be received inthe notches of one of the parts and the outwardlycurved portion of said spring be' ing adapted to be-received iii thenotches of the other part. l

5. In an adJusting device: having a screw threaded connection and beingadjustable relative to each other; a spring carried by the device andhaving a longitudinally extending end [portion: a plurality ofcircumfer- `entially equally spaced recesses on one member engageable bythe end portion; and a plurality` of circumferentially spaced recesseson the other member also engageable by said end portion; said endportion of the spring being operably movable longitudinally.

- 6. In an adjusting device: a pair of threadably connected membersmovable relative to each other; an annular flange on one of said membershaving a plurality of equally shaped notches about the periphery thereofan annular ring on the other member having a flange extending toward thefirst mentioned flange and having a plurality of equally spaced notchestherein; a spring coiled about the device between the flanges and havinglongitudinally extending end portion including a the locking means beinglongitudinally movable. c

2. In an adjusting device: an externally threaded part; an annularflange on said part, a plurality of equally spaced notches disposedabout the periphery of said ilange; a member-.threadably received on thepart; an annular ilange on bent section adjacent one end adapted to bereceived in the notches of the second mentioned flange, the other end ofsaid end portion being adapted to be slidably received in the notches ofthe first flange. A l

'1. In an adjusting device: a pair of threadably connected membersmovable relativev to each other; an annular ilange on one of saidmembers; an annular ilange on the 'other member spaced laterally fromsame; a plurality of notches substantially equally spaced about theilanges; and locking means so constructed and arranged as to engagenotches in the respective ilanges for mainsaid member of substantiallythe same diameter 7s taining the members against movement relative iapair of vmembers on said sleeve and member; engageable means equallyspaced en said flanges; there being a different number of said means forone flange than the other; and locking means engageable with therespective engageable means for preventing movement of the partsrelative to each other.

9. In a fuel pump for supplying fuel to an enginel comprising: ahousing; a plurality of pumping plungers crcularly arranged and spacedapart withinthe housing; an annular channel for each plunger; a passagein each plunger connected with the channel thereof a bypass sleeveslidable on each plunger for controlling the respective annular channelsand vadapted to vary the effective stroke of the respective plunger; amember carrying the sleeve; a support for said members; flanges onsaidsleeve and member the circumferences of which are substantially thesame; engageable means equally spaced about the periphery of theflanges, there being a different number of means for one flange than theother;

A respective engageable means for preventing moveannular channel thereofadjustable for varying the effective stroke of the plunger; a membercarrying the sleeve; a scale for the sleeve having engageable meansforming a part thereof and equally spaced apart thereon; a scale for themember of substantially the same length as the scale for the sleeve landhaving engageable means forming a. part thereof equally spaced apart,the

and resilient locking means engageable with the engageable means o'f onescale being spaced apart `a greater distance than those of the otherscale;

resilient locking means disposed between the scales and cooperating withsaid engageable means for locking the sleeve and member together; anannular groove in the member; and a plate having peripheral notchescircumferentially spaced apart in which the groove portions of themembers are snugly but rotatably received. said members being heldagainst lateral movement relative to the plate by the respective sidewalls of the groove. l

l GEORGE P. LUM.

